linux-stable.git/kernel/bpf, branch v5.4.201

bpf: Fix incorrect memory charge cost calculation in stack_map_alloc()

2022-06-22T12:11:02+00:00

commit b45043192b3e481304062938a6561da2ceea46a6 upstream.

This is a backport of the original upstream patch for 5.4/5.10.

The original upstream patch has been applied to 5.4/5.10 branches, which
simply removed the line:

  cost += n_buckets * (value_size + sizeof(struct stack_map_bucket));

This is correct for upstream branch but incorrect for 5.4/5.10 branches,
as the 5.4/5.10 branches do not have the commit 370868107bf6 ("bpf:
Eliminate rlimit-based memory accounting for stackmap maps"), so the
bpf_map_charge_init() function has not been removed.

Currently the bpf_map_charge_init() function in 5.4/5.10 branches takes a
wrong memory charge cost, the

  attr->max_entries * (sizeof(struct stack_map_bucket) + (u64)value_size))

part is missing, let's fix it.

Cc:  # 5.4.y
Cc:  # 5.10.y
Signed-off-by: Yuntao Wang 
Signed-off-by: Greg Kroah-Hartman

bpf: Fix excessive memory allocation in stack_map_alloc()

2022-06-14T16:11:32+00:00

[ Upstream commit b45043192b3e481304062938a6561da2ceea46a6 ]

The 'n_buckets * (value_size + sizeof(struct stack_map_bucket))' part of the
allocated memory for 'smap' is never used after the memlock accounting was
removed, thus get rid of it.

[ Note, Daniel:

Commit b936ca643ade ("bpf: rework memlock-based memory accounting for maps")
moved `cost += n_buckets * (value_size + sizeof(struct stack_map_bucket))`
up and therefore before the bpf_map_area_alloc() allocation, sigh. In a later
step commit c85d69135a91 ("bpf: move memory size checks to bpf_map_charge_init()"),
and the overflow checks of `cost >= U32_MAX - PAGE_SIZE` moved into
bpf_map_charge_init(). And then 370868107bf6 ("bpf: Eliminate rlimit-based
memory accounting for stackmap maps") finally removed the bpf_map_charge_init().
Anyway, the original code did the allocation same way as /after/ this fix. ]

Fixes: b936ca643ade ("bpf: rework memlock-based memory accounting for maps")
Signed-off-by: Yuntao Wang 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20220407130423.798386-1-ytcoode@gmail.com
Signed-off-by: Sasha Levin

bpf: Add kconfig knob for disabling unpriv bpf by default

2022-02-16T11:52:49+00:00

commit 08389d888287c3823f80b0216766b71e17f0aba5 upstream.

Add a kconfig knob which allows for unprivileged bpf to be disabled by default.
If set, the knob sets /proc/sys/kernel/unprivileged_bpf_disabled to value of 2.

This still allows a transition of 2 -> {0,1} through an admin. Similarly,
this also still keeps 1 -> {1} behavior intact, so that once set to permanently
disabled, it cannot be undone aside from a reboot.

We've also added extra2 with max of 2 for the procfs handler, so that an admin
still has a chance to toggle between 0 <-> 2.

Either way, as an additional alternative, applications can make use of CAP_BPF
that we added a while ago.

Signed-off-by: Daniel Borkmann 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/74ec548079189e4e4dffaeb42b8987bb3c852eee.1620765074.git.daniel@iogearbox.net
[fllinden@amazon.com: backported to 5.4]
Signed-off-by: Frank van der Linden 
Signed-off-by: Greg Kroah-Hartman

bpf: Fix integer overflow in argument calculation for bpf_map_area_alloc

2021-12-17T09:12:24+00:00

commit 7dd5d437c258bbf4cc15b35229e5208b87b8b4e0 upstream.

In 32-bit architecture, the result of sizeof() is a 32-bit integer so
the expression becomes the multiplication between 2 32-bit integer which
can potentially leads to integer overflow. As a result,
bpf_map_area_alloc() allocates less memory than needed.

Fix this by casting 1 operand to u64.

Fixes: 0d2c4f964050 ("bpf: Eliminate rlimit-based memory accounting for sockmap and sockhash maps")
Fixes: 99c51064fb06 ("devmap: Use bpf_map_area_alloc() for allocating hash buckets")
Fixes: 546ac1ffb70d ("bpf: add devmap, a map for storing net device references")
Signed-off-by: Bui Quang Minh 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20210613143440.71975-1-minhquangbui99@gmail.com
Signed-off-by: Connor O'Brien 
Signed-off-by: Greg Kroah-Hartman

bpf: Fix the off-by-two error in range markings

2021-12-14T13:48:59+00:00

commit 2fa7d94afc1afbb4d702760c058dc2d7ed30f226 upstream.

The first commit cited below attempts to fix the off-by-one error that
appeared in some comparisons with an open range. Due to this error,
arithmetically equivalent pieces of code could get different verdicts
from the verifier, for example (pseudocode):

  // 1. Passes the verifier:
  if (data + 8 > data_end)
      return early
  read *(u64 *)data, i.e. [data; data+7]

  // 2. Rejected by the verifier (should still pass):
  if (data + 7 >= data_end)
      return early
  read *(u64 *)data, i.e. [data; data+7]

The attempted fix, however, shifts the range by one in a wrong
direction, so the bug not only remains, but also such piece of code
starts failing in the verifier:

  // 3. Rejected by the verifier, but the check is stricter than in #1.
  if (data + 8 >= data_end)
      return early
  read *(u64 *)data, i.e. [data; data+7]

The change performed by that fix converted an off-by-one bug into
off-by-two. The second commit cited below added the BPF selftests
written to ensure than code chunks like #3 are rejected, however,
they should be accepted.

This commit fixes the off-by-two error by adjusting new_range in the
right direction and fixes the tests by changing the range into the
one that should actually fail.

Fixes: fb2a311a31d3 ("bpf: fix off by one for range markings with L{T, E} patterns")
Fixes: b37242c773b2 ("bpf: add test cases to bpf selftests to cover all access tests")
Signed-off-by: Maxim Mikityanskiy 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20211130181607.593149-1-maximmi@nvidia.com
Signed-off-by: Greg Kroah-Hartman

bpf: Prevent increasing bpf_jit_limit above max

2021-11-17T08:48:20+00:00

[ Upstream commit fadb7ff1a6c2c565af56b4aacdd086b067eed440 ]

Restrict bpf_jit_limit to the maximum supported by the arch's JIT.

Signed-off-by: Lorenz Bauer 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20211014142554.53120-4-lmb@cloudflare.com
Signed-off-by: Sasha Levin

bpf: Fix integer overflow in prealloc_elems_and_freelist()

2021-10-13T08:08:18+00:00

[ Upstream commit 30e29a9a2bc6a4888335a6ede968b75cd329657a ]

In prealloc_elems_and_freelist(), the multiplication to calculate the
size passed to bpf_map_area_alloc() could lead to an integer overflow.
As a result, out-of-bounds write could occur in pcpu_freelist_populate()
as reported by KASAN:

[...]
[   16.968613] BUG: KASAN: slab-out-of-bounds in pcpu_freelist_populate+0xd9/0x100
[   16.969408] Write of size 8 at addr ffff888104fc6ea0 by task crash/78
[   16.970038]
[   16.970195] CPU: 0 PID: 78 Comm: crash Not tainted 5.15.0-rc2+ #1
[   16.970878] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
[   16.972026] Call Trace:
[   16.972306]  dump_stack_lvl+0x34/0x44
[   16.972687]  print_address_description.constprop.0+0x21/0x140
[   16.973297]  ? pcpu_freelist_populate+0xd9/0x100
[   16.973777]  ? pcpu_freelist_populate+0xd9/0x100
[   16.974257]  kasan_report.cold+0x7f/0x11b
[   16.974681]  ? pcpu_freelist_populate+0xd9/0x100
[   16.975190]  pcpu_freelist_populate+0xd9/0x100
[   16.975669]  stack_map_alloc+0x209/0x2a0
[   16.976106]  __sys_bpf+0xd83/0x2ce0
[...]

The possibility of this overflow was originally discussed in [0], but
was overlooked.

Fix the integer overflow by changing elem_size to u64 from u32.

  [0] https://lore.kernel.org/bpf/728b238e-a481-eb50-98e9-b0f430ab01e7@gmail.com/

Fixes: 557c0c6e7df8 ("bpf: convert stackmap to pre-allocation")
Signed-off-by: Tatsuhiko Yasumatsu 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20210930135545.173698-1-th.yasumatsu@gmail.com
Signed-off-by: Sasha Levin

bpf: Add oversize check before call kvcalloc()

2021-09-30T08:09:25+00:00

[ Upstream commit 0e6491b559704da720f6da09dd0a52c4df44c514 ]

Commit 7661809d493b ("mm: don't allow oversized kvmalloc() calls") add the
oversize check. When the allocation is larger than what kmalloc() supports,
the following warning triggered:

WARNING: CPU: 0 PID: 8408 at mm/util.c:597 kvmalloc_node+0x108/0x110 mm/util.c:597
Modules linked in:
CPU: 0 PID: 8408 Comm: syz-executor221 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:kvmalloc_node+0x108/0x110 mm/util.c:597
Call Trace:
 kvmalloc include/linux/mm.h:806 [inline]
 kvmalloc_array include/linux/mm.h:824 [inline]
 kvcalloc include/linux/mm.h:829 [inline]
 check_btf_line kernel/bpf/verifier.c:9925 [inline]
 check_btf_info kernel/bpf/verifier.c:10049 [inline]
 bpf_check+0xd634/0x150d0 kernel/bpf/verifier.c:13759
 bpf_prog_load kernel/bpf/syscall.c:2301 [inline]
 __sys_bpf+0x11181/0x126e0 kernel/bpf/syscall.c:4587
 __do_sys_bpf kernel/bpf/syscall.c:4691 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:4689 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4689
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported-by: syzbot+f3e749d4c662818ae439@syzkaller.appspotmail.com
Signed-off-by: Bixuan Cui 
Signed-off-by: Alexei Starovoitov 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/bpf/20210911005557.45518-1-cuibixuan@huawei.com
Signed-off-by: Sasha Levin

bpf: Fix pointer arithmetic mask tightening under state pruning

2021-09-15T07:47:39+00:00

commit e042aa532c84d18ff13291d00620502ce7a38dda upstream.

In 7fedb63a8307 ("bpf: Tighten speculative pointer arithmetic mask") we
narrowed the offset mask for unprivileged pointer arithmetic in order to
mitigate a corner case where in the speculative domain it is possible to
advance, for example, the map value pointer by up to value_size-1 out-of-
bounds in order to leak kernel memory via side-channel to user space.

The verifier's state pruning for scalars leaves one corner case open
where in the first verification path R_x holds an unknown scalar with an
aux->alu_limit of e.g. 7, and in a second verification path that same
register R_x, here denoted as R_x', holds an unknown scalar which has
tighter bounds and would thus satisfy range_within(R_x, R_x') as well as
tnum_in(R_x, R_x') for state pruning, yielding an aux->alu_limit of 3:
Given the second path fits the register constraints for pruning, the final
generated mask from aux->alu_limit will remain at 7. While technically
not wrong for the non-speculative domain, it would however be possible
to craft similar cases where the mask would be too wide as in 7fedb63a8307.

One way to fix it is to detect the presence of unknown scalar map pointer
arithmetic and force a deeper search on unknown scalars to ensure that
we do not run into a masking mismatch.

Signed-off-by: Daniel Borkmann 
Acked-by: Alexei Starovoitov 
Signed-off-by: Greg Kroah-Hartman 
[OP: adjusted context in include/linux/bpf_verifier.h for 5.4]
Signed-off-by: Ovidiu Panait 
Signed-off-by: Greg Kroah-Hartman

bpf: verifier: Allocate idmap scratch in verifier env

2021-09-15T07:47:38+00:00

commit c9e73e3d2b1eb1ea7ff068e05007eec3bd8ef1c9 upstream.

func_states_equal makes a very short lived allocation for idmap,
probably because it's too large to fit on the stack. However the
function is called quite often, leading to a lot of alloc / free
churn. Replace the temporary allocation with dedicated scratch
space in struct bpf_verifier_env.

Signed-off-by: Lorenz Bauer 
Signed-off-by: Alexei Starovoitov 
Acked-by: Edward Cree 
Link: https://lore.kernel.org/bpf/20210429134656.122225-4-lmb@cloudflare.com
Signed-off-by: Greg Kroah-Hartman 
[OP: adjusted context for 5.4]
Signed-off-by: Ovidiu Panait 
Signed-off-by: Greg Kroah-Hartman